This invention relates to methods and apparatus for modifying human voice sounds to produce other voice sounds which are intelligible but which do not sound like the original voice sounds.
In activities such as aircraft flight training simulations, the trainee hears, and must respond to, simulated radio communications from several sources, e.g., an airport controller, ground controllers at various locations, and other aircraft in his vicinity. In a real situation, each of these radio communications would have recognizably different sound characteristics, largely because of the different voice characteristics of the various speakers originating them. In a flight simulation, however, one speaker (i.e., the person controlling the simulation) generally originates with his own voice all of the simulated radio cummunications the trainee hears. The trainee therefore hears only one voice playing several different roles and an important element of realism is missing from the simulation.
It is therefore an object of this invention to provide methods and apparatus for modifying human voice sounds to produce other voice sounds which are intelligible but which are not recognizable as the original voice sounds.
In the flight training simulation situation described above, the object of the invention is to modify a normal human voice sound so that it sounds like one or more other normal human voice sounds. This application of the invention may be referred to for convenience as "normal voice in and modified normal voice out". There are, however, other applications of the invention in which either (1) the original voice sounds are not normal voice sounds and the invention is used to modify those sounds to produce more normal and more intelligible voice sounds, or (2) the original voice sounds are normal and the invention is used to modify those sounds to produce abnormal voice sounds which are still intelligible. An example of the first of the foregoing alternatives is modifying the voice sounds of a person such as an underwater diver whose voice sounds are distorted by breathing a combination of gases having density very different from the density of atmospheric air. Typically, the gases supplied to an underwater diver have a large constituent of helium in place of the nitrogen which makes up most of atmospheric air. The diver is therefore breathing a combination of gases which is much less dense than atmospheric air and the pitch of his voice is therefore raised to the point where his voice sounds are virtually unintelligible. This invention can be used to at least partially restore these voice sounds to normal pitch and greatly improve their intelligibility.
An example of the second alternative mentioned above is cartoon sound tracks in which it is desired to modify normal voice sounds to produce abnormal but still intelligible voice sounds for comic or similar effects.
In view of the foregoing, it is a further object of this invention to provide methods and apparatus for modifying distorted human voice sounds to produce voice sounds which are more normal and more intelligible.
It is another object of the invention to provide methods and apparatus for modifying normal human voice sounds to produce voice sounds which are abnormal but still intelligible.